Active minimization of the sidelobes of radiating apertures

A novel technique for suppressing sidelobes as well as increasing the mainlobe level of radiating apertures is presented. The technique involves placing a separately excited wire along the diffracting edge of the aperture so as to enhance the mainlobe and to suppress the sidelobes of the radiating aperture. The beamwidths of the resulting Eand H planes of a circular waveguide loaded by an active wire loop are found to be almost identical in a particular experimental case. Furthermore, the E and H plane patterns approach each other since the sidelobe levels are decreased significantly in the E plane and by about the same amount as they are increased in the H plane. A significant increase in the main-to-sidelobe ratio is also obtained when this technique is applied to radiating fields from circular apertures in a full conducting plane and to the diffraction from apertures between two semi-infinite conducting wedges.